Key Items in Devil May Cry 3: Dante's Awakening

Astronomical Board
The Astronomical Board is an astrological device powered by time which displays the endless void. It can be found during Mission 4 in the Astral Chamber, and can be used to raise the gates set along the stairs in the Chamber of Echoes in Mission 5.

Vajura
Vajura is a model of an ancient trident-like weapon used to control lightning. This is merely an ornament and has no battle use. It can be collected in the Chamber of Echoes in Mission 5 once the Astronomical Board is used. Vajura itself is needed for the device which raises up the cage in the Living Statue Room where the Soul Of Steel lies.

Soul of Steel
Soul of Steel is the essence of a powerful and fearless soul. It is found by Dante within a cage in Living Statue Room during Mission 05,after he acquires and uses Vajura. It allows the possessor to walk on air over the abyss in the Endless Infernum, and is used to open the door to the Surge of Fortunas.

Orihalcon
Orihalcon is a stone-like material which can be used as an energy source. Dante finds several pieces of Orihalcon during his time in Temen-ni-gru, and he uses these fragments to power several mechanisms. These mechanisms are, namely, the elevator from the Chamber of Echoes to the Upper Temen-ni-gru, the door to the Lair of Judgement, and the Devilsprout Lift.

Dante finds one orihalcon in Mission 07 and uses it to power an elevator. The next is found in Mission 13. The third orihalcon must be pieced to gether from three fragments found in Mission 15 and one found in Mission 16.

Siren's Shriek
Siren's Shriek is a teardrop-like vial found in the Room of Tranquil Souls, during Mission 7, and is used in the Chamber of Echoes to open the door blocked by "crimson fire".

Crystal Skull
Crystal Skull is a mysterious crystal carving resembling human skull. It can be picked up in the Cursed Skull Chamber in Mission 07, once the skull cage is broken, and is used to unlock the door to the Moonlight Mile in the same mission.

Ignis Fatuus
Ignis Fatuus is Leviathan's power source. It is composed of souls of those sent to hell for various reasons. It can be found in Mission 8 in Leviathan's Retina, but is covered by a membranous curtain. It can only be picked up once its greed for orbs is satisfied, and is used to dissolve the membrane leading to Leviathan's Heart.

Ambrosia
Ambrosia is a demonic fruit which humankind is forbidden to even touch. It unlocks the door to the Sunken Opera House and can be found in the second Provisions Storeroom in Mission 9.

Stone Mask
Stone Mask is a magical mask created by an ancient priest. It is used to raise the bridge to the Neo-Generator on the Subterranean Lake. It can be found in Mission 10 in a distant part of Limestone Cavern which is only accessible through the Sunken Opera House, and it is used to raise a sunken pathway to reach the Neo-Generator.

Neo-Generator
There are two Neo-Generators which Dante finds, both of which are used to move The Rotating Bridge.

The first Neo-Generator can be found on an island on the Subterranean Lake in Mission 10. It is accessible only by a bridge raised by the power of the Stone Mask. It is used at the beginning of Mission 11 to rotate the main bridge.

The second generator, called Haywire Neo-Generator is taken by Dante at the beginning of Mission 12, in the Torture Chamber just after defeating Beowulf. However, Dante starts to feel weakened and falls on his knees. Jester immediately appears, and after some threatening from Dante's side he explains that the generator is the only key to move forward. He also tells him that the generator drains the soul of those who hold it in exchange for power. In gameplay terms it results in Dante constantly losing his health in exchange for an infinite Devil Trigger which cannot be turned off. The damage received from Haywire Generator isn't counted in total mission score.

Golden Sun & Onyx Moonshard
Golden Sun and Onyx Moonshard are a pair of figurines used to unlock the seal in the Sun & Moon chamber in Mission 16. The sculptures contrast each other. The first can be found in the Waking Sun Chamber, while the second is hidden in the Chamber of Sins.

Samsara
Samsara is a sculpture symbolizing time-space continuum, which can be found in Infinity Nirvana in Mission 19 once all demons are slain before the room's hourglass drains. It is used in Nirvana of Illusions to break the Room of the Fallen Ones—Nirvana of Illusions—Infinity Nirvana—Lost Souls Nirvana portal circle and open the path to The End of the Line.